| 1. |
- Cintas Sanchez, Olivia, 1982, et al.
(författare)
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THE CLIMATE BENEFITS OF INCREASED FOREST BIOENERGY USE IN SWEDEN: EVALUATION AT DIFFERENT SCALES
- 2014
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Ingår i: World Bioenergy 2014 Proceedings. ; , s. 133-139
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Konferensbidrag (refereegranskat)abstract
- Forest bioenergy has gained attention as an alternative to replace fossil fuels and mitigate climate change; however, in recent years its climate benefit has been questioned. The aim of this paper is to (i) present results from an assessment of the carbon (C) balance for Swedish bioenergy systems that use forest biomass from long-rotation forestry as feedstock; (ii) show how methodological choices and assumptions influence the outcome of the assessment; and (iii) discuss the climate effect of increasing forest harvest for energy use in Sweden. To achieve this purpose, an assessment framework is developed which consists of two linked models: the first one is the Q model, used to quantify the biogenic C balances associated with forest management and the second one is the CAfBio, used to account for forest product flows up to the point when the C is released into the atmosphere. Modeling results depend on many factors, with some important ones being harvest intensity, changes in forest management and the emissions intensity of the baseline scenario, which determines the C savings from using forest products. However, the results of the study support the conclusion that increased use of forest biomass for bioenergy can deliver substantial C savings.
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| 2. |
- Franklin, Oskar, et al.
(författare)
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Pine forest floor carbon accumulation in response to N and PK additions : Bomb C-14 modelling and respiration studies
- 2003
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Ingår i: Ecosystems (New York. Print). - : Springer Science and Business Media LLC. - 1432-9840 .- 1435-0629. ; 6:7, s. 644-658
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Tidskriftsartikel (refereegranskat)abstract
- The addition of nitrogen via deposition alters the carbon balance of temperate forest ecosystems by affecting both production and decomposition rates. The effects of 20 years of nitrogen (N) and phosphorus and potassium (PK) additions were studied in a 40-year-old pine stand in northern Sweden. Carbon fluxes of the forest floor were reconstructed using a combination of data on soil 14C, tree growth, and litter decomposition. N-only additions caused an increase in needle litterfall, whereas both N and PK additions reduced long-term decomposition rates. Soil respiration measurements showed a 40% reduction in soil respiration for treated compared to control plots. The average age of forest floor carbon was 17 years. Predictions of future soil carbon storage indicate an increase of around 100% in the next 100 years for the N plots and 200% for the NPK plots. As much as 70% of the increase in soil carbon was attributed to the decreased decomposition rate, whereas only 20% was attributable to increased litter production. A reduction in decomposition was observed at a rate of N addition of 30 kg C ha−1 y−1, which is not an uncommon rate of N deposition in central Europe. A model based on the continuous-quality decomposition theory was applied to interpret decomposer and substrate parameters. The most likely explanations for the decreased decomposition rate were a fertilizer-induced increase in decomposer efficiency (production-to-assimilation ratio), a more rapid rate of decrease in litter quality, and a decrease in decomposer basic growth rate.
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| 3. |
- Majdi, Hooshang, et al.
(författare)
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Measuring Fine Root Turnover in Forest Ecosystems
- 2005
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 276:1-2, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Development of direct and indirect methods for measuring root turnover and the status of knowledge on fine root turnover in forest ecosystems are discussed. While soil and ingrowth cores give estimates of standing root biomass and relative growth, respectively, minirhizotrons provide estimates of median root longevity (turnover time) i.e., the time by which 50% of the roots are dead. Advanced minirhizotron and carbon tracer studies combined with demographic statistical methods and new models hold the promise of improving our fundamental understanding of the factors controlling root turnover. Using minirhizotron data, fine root turnover (y−1) can be estimated in two ways: as the ratio of annual root length production to average live root length observed and as the inverse of median root longevity. Fine root production and mortality can be estimated by combining data from minirhizotrons and soil cores, provided that these data are based on roots of the same diameter class (e.g., < 1 mm in diameter) and changes in the same time steps. Fluxes of carbon and nutrients via fine root mortality can then be estimated by multiplying the amount of carbon and nutrients in fine root biomass by fine root turnover. It is suggested that the minirhizotron method is suitable for estimating median fine root longevity. In comparison to the minirhizotron method, the radio carbon technique favor larger fine roots that are less dynamics. We need to reconcile and improve both methods to develop a more complete understanding of root turnover.
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| 4. |
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| 5. |
- Majdi, Hooshang, et al.
(författare)
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Root respiration data and minirhizotron observations conflict with root turnover estimates from sequential soil coring
- 2007
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 22:4, s. 299-303
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Tidskriftsartikel (refereegranskat)abstract
- The turnover of fine roots in northern coniferous forests has conventionally been assumed to be rapid, in line with results from sequential coring in the late 1970s in a Swedish Scots pine stand (SWECON project) where a rate of 7.4 year(-1) was estimated. New quantifications of the root respiration in other stands motivated a recalculation of the SWECON data; an indirect estimation of the turnover rate was much slower, about 2.1 year(-1). As a consequence, fine-root production is considered to be much lower than in previous estimates. Furthermore, direct observations of Norway spruce fine roots (< 1 mm) from minirhizotrons in Sweden, including a site close to the SWECON site, indicated a slower estimate, with fine-root turnover rate of 0.9 year
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| 6. |
- Sayin, Volkan I., 1983, et al.
(författare)
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Loss of One Copy of Zfp148 Reduces Lesional Macrophage Proliferation and Atherosclerosis in Mice by Activating p53
- 2014
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Ingår i: Circulation Research. - : Ovid Technologies (Wolters Kluwer Health). - 0009-7330 .- 1524-4571. ; 115:9, s. 781-791
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Tidskriftsartikel (refereegranskat)abstract
- Rationale: Cell proliferation and cell cycle control mechanisms are thought to play central roles in the pathogenesis of atherosclerosis. The transcription factor Zinc finger protein 148 (Zfp148) was shown recently to maintain cell proliferation under oxidative conditions by suppressing p53, a checkpoint protein that arrests proliferation in response to various stressors. It is established that inactivation of p53 accelerates atherosclerosis, but whether increased p53 activation confers protection against the disease remains to be determined. Objective: We aimed to test the hypothesis that Zfp148 deficiency reduces atherosclerosis by unleashing p53 activity. Methods and Results: Mice harboring a gene-trap mutation in the Zfp148 locus (Zfp148(gt/+)) were bred onto the apolipoprotein E (Apoe)(-/-) genetic background and fed a high-fat or chow diet. Loss of 1 copy of Zfp148 markedly reduced atherosclerosis without affecting lipid metabolism. Bone marrow transplantation experiments revealed that the effector cell is of hematopoietic origin. Peritoneal macrophages and atherosclerotic lesions from Zfp148(gt/+)Apoe(-/-) mice showed increased levels of phosphorylated p53 compared with controls, and atherosclerotic lesions contained fewer proliferating macrophages. Zfp148(gt/+) Apoe(-/-) mice were further crossed with p53-null mice (Trp53(-/-) [the gene encoding p53]). There was no difference in atherosclerosis between Zfp148(gt/+) Apoe(-/-) mice and controls on a Trp53(+/-) genetic background, and there was no difference in levels of phosphorylated p53 or cell proliferation. Conclusions: Zfp148 deficiency increases p53 activity and protects against atherosclerosis by causing proliferation arrest of lesional macrophages, suggesting that drugs targeting macrophage proliferation may be useful in the treatment of atherosclerosis.
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